1. Field of the Invention
The present invention relates to compositions for controlling the growth of microorganisms on a variety of substrates and in aqueous systems. More particularly, the invention relates to combinations of propiconazole, also known as (RS)-1-2-(2,4-dichlorophenyl)-2-propyl-1,3-dioxalan-2-ylmethyl!-1H-1,2,4- triazole, with dodecylamine or a dodecylamine salt. The invention also relates to the use of such combinations as microbicides.
2. Background of the Invention
A large variety of commercial, industrial, agricultural, and wood materials or products are subject to microbiological attack or degradation which reduces or destroys their economic value. Examples of such materials or products include surface coatings, lumber, seeds, plants, leather and plastics. The various temperatures at which such materials or products are manufactured, stored, or used as well as their intrinsic characteristics make them susceptible to growth, attack, and degradation by common microorganisms such as algae, fungi, yeasts, and bacteria. These microorganisms may be introduced during a manufacturing or other industrial process, by exposure to air, tanks, pipes, equipment, and humans. They can also be introduced while using a material or product, for example, by multiple openings and reclosures of packages or from stirring or removing material with contaminated objects.
Aqueous systems are also highly subject to microbiological growth, attack, and degradation. The aqueous system may be a fresh, brackish or saltwater system. Exemplary aqueous systems include, but are not limited to, latexes, surfactants, dispersants, stabilizers, thickeners, adhesives, starches, waxes, proteins, emulsifying agents, cellulose products, metal worlking fluids, cooling water, waste water, aqueous emulsions, aqueous detergents, coating compositions, paint compositions, and resins formulated in aqueous solutions, emulsions or suspensions. These systems frequently contain relatively large amounts of water and organic material causing them to be environments well-suited for microbiologic growth and thus attack and degradation.
Microbiological degradation of aqueous systems may manifest itself as a variety of problems, such as loss of viscosity, gas formation, objectionable odors, decreased pH, emulsion breaking, color change, and gelling. Additionally, microbiological deterioration of aqueous systems can cause fouling of the related water-handling system, which may include cooling towers, pumps, heat exchangers, and pipelines, heating systems, scrubbing systems, and other similar systems.
Microbiological degradation can have a direct adverse economic impact when it occurs in industrial process waters, for example in cooling waters, metal working fluids, or other recirculating water systems such as those used in papermaking or textile manufacture. If not controlled, microbiological degradation of industrial process waters can interfere with process operations, lower process efficiency, waste energy, plug the water-handling system, and even degrade product quality.
For example, cooling water systems used in power plants, refineries, chemical plants, air-conditioning systems, and other industrial operations frequently encounter microbiological degradation problems. Airborne organisms entrained from cooling towers as well as waterborne organisms from the system's water supply commonly contaminate these aqueous systems. The water in such systems generally provides an excellent growth medium for these organisms. Aerobic and heliotropic organisms flourish in the towers. Other organisms grow in and colonize such areas as the tower sump, pipelines, heat exchangers, etc. If not controlled, the resulting microbiological degradation can plug the towers, block pipelines, and coat heat-transfer surfaces with layers of slime and other biologic mats. This prevents proper operation, reduces cooling efficiency and, perhaps more importantly, increases the costs of the overall process.
Industrial processes subject to microbiological degradation also include papermaking, the manufacture of pulp, paper, paperboard, etc. and textile manufacture, particularly water-laid non-woven textiles. These industrial processes generally recirculate large amounts of water under conditions which favor the growth of microbiological degradation organisms.
Paper machines, for example, handle very large volumes of water in recirculating systems called "white water systems." The furnish to a paper machine typically contains only about 0.5% of fibrous and non-fibrous papermaking solids, which means that for each ton of paper almost 200 tons of water pass through the headbox. Most of this water recirculates in the white water system. White water systems provide excellent growth media for microbiological degradation organisms. That growth can result in the fromation of slime and other deposits in headboxes, waterlines, and papermaking equipment. Such microbiological degradation not only can interfere with water and stock flows, but when loose, can cause spots, holes, and bad odors in the paper as well as web breaks, all of which translate into costly disruptions in paper machine operations.
Slime formation can occur in other aqueous systems including fresh, brackish or salt water systems. Slime consists of matted deposits of microorganisms, fibers and debris. It may be stringy, pasty, rubbery, tapioca-like, or hard, and may have a characteristic undesirable odor that is different from that of the aqueous system in which it formed. The microorganisms involved in its formation are primarily different species of spore-forming and nonspore-forming bacteria, particularly capsulated forms of bacteria which secrete gelatinous substances that envelop or encase the cells. Slime microorganisms also include filamentous bacteria, filamentous fungi of the mold type, yeast, and yeast-like organisms. Slime reduces yields in production and causes plugging, bulking, and other problems in industrial water systems.
Various chemicals known as industrial microbicides have been used to prevent microbiological deterioration or degradation of industrial systems, raw materials, and products. Some of these biocides, however, are of questionable practical utility because they have undesirable odors, are high in cost, show low degree of effectiveness or create hazards with respect to storage, use, or handling. For instance, the use of such popular industrial microbicides as organomercurial compounds, organotin compounds and chlorinated phenols have come under great regulatory pressure in recent times because of their high toxicity and concern about their adverse effects on the environment.
Propiconazole, also known as (RS)-1-2-(2,4-dichlorophenyl)-2-propyl-1,3-dioxalan-2ylmethyl!1H-1,2,4-tr iazole, is one commercial biocide which has been shown to have a reasonably good toxicological profile and biocidal activity. However, at low concentrations, propiconazole may have a relatively narrow antimicrobial spectrum and may not completely prevent the growth of microorganisms.
Despite the existence of current microbicides, workers in the trade have continued to seek improved biocides which possess low toxicity while exhibiting a prolonged biocidal effect at normal use levels. The improved microbicide should also preferably be more economical and cost-effective offering equal or better protection at lower cost and lower concentration. The concentration of conventional microbicides and the corresponding treatment costs for such use, can be relatively high. Thus, important factors in the search for improved microbicides include the duration of microbicidal effect, the ease of use, and the effectiveness of the microbicide per unit weight.